Transitions in the sliding wear mechanisms of binary Cu-Al alloys having a range of solute contents and microstructures

Abstract

Sliding wear damage to non-lubricated metallic bearing surfaces results from the dissipation of frictional work. Damage features at or near worn surfaces depend on alloy-specific modes of deformation that are influenced by stacking fault energy (SFE) and other microstructural properties. Metal pairs having similar friction coefficients do not necessarily wear equally due to differences in energy partition. Dissipative mechanisms include highly-deformed layer (HDL) formation, deformation twinning, recrystallization, amorphization, and texturing. In some tribosystems, a portion of the frictional work is dissipated in third-body layers. HDL thickness can vary from grain-to-grain, depending on crystallographic orientation relative to the sliding direction. Thus, the energy used in texturing can also vary grain-by-grain. Composition and surface processing methods affect the manner and degree of friction/wear correlation. Transitions in wear mechanisms are investigated in a series of Cu-Al binary alloys ranging from 0 to 15 wt% Al that are processed by different routes. These bronzes were worn against bearing steels in a non-lubricated block-on-ring configuration. Application of established and less common imaging methods supports the transition from sharpened dislocation cell formation at higher SFE to deformation twinning at lower SFE. At the wear process level, primary and secondary wear debris affect model development because their relative influence changes over time.